Automated nuclear fuel rod pattern loading system

ABSTRACT

Apparatus for loading fuel rods in a desired enrichment pattern includes a carrousel, an elongated fuel rod storage magazine, and a fuel rod verify and feed workstation and a magazine holder and indexing mechanism disposed between the carrousel and the magazine. The carrousel has a plurality of gondolas movable mounted thereon for stocking fuel rods of known enrichments. The magazine defines a matrix of elongated slots open at their forward ends for receiving fuel rods. The workstation defines a fuel rod feed path extending between the carrousel and the magazine and is adapted to receive successively one at a time along the feed path at its upstream end fuel rods from selected ones of the carrousel gondolas. The workstation includes an optical scanning and reading unit located along the feed path for verifying the identity of the fuel rods successively one at a time and a fuel rod feeding mechanism for successively feeding one at a time along the feed path the verified fuel rods into selected ones of the slots in the magazine. The magazine holder and indexing mechanism movably supports the magazine and is actuatable for moving the magazine along X-Y axes to successively align one at a time selected ones of its slots with the feed path for loading in the magazine the successive fuel rods in a desired enrichment pattern.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to nuclear fuel rod loadingsystems and, more particularly, is concerned with an automated systemfor loading fuel rods in a desired pattern into a magazine.

2. Description of the Prior Art

Fuel assemblies in nuclear reactors of the type utilized in powergeneration generally incorporate numerous fuel rods arranged inspaced-apart relationship within a skeleton including top and bottomnozzles or tie plates between which the fuel rods extend. Each fuel rodgenerally includes a metallic tube sealed at its opposite ends by enplugs and a stack of enriched nuclear fuel pellets contained within thetube between the end plugs. All of the fuel pellets within a given fuelrod are usually of the same enrichment, but fuel rods of the same ordifferent enrichments can be used in a particular fuel assemblydepending upon the reactor type. For example, a pressurized waterreactor (PWR) typically utilizes fuel assemblies with fuel rods of thesame enrichment in a particular fuel assembly, whereas a boiling waterreactor BWR) utilizes fuel assemblies of multiple enrichments whichrequire the fuel rods to be arranged in a particular pattern.

It will be appreciated that fuel rod loading systems must accommodateprocedures for properly identifying fuel rods of particular enrichmentsand for tracking them in carrying out loading of the fuel rods into thedesired patterns in which they will reside in fuel assemblies.Representative prior art fuel rod loading systems are disclosed inpatents to Ahmed et al (U.S. Pat. No. 4,625,396), Schoenig, Jr. et al(U.S. Pat. No. 4,649,632) and Vere et al (French Pat. No. 2,579,359).

In the fuel rod loading system disclosed by the above-cited Ahmed et alpatent, which is assigned to the same assignee as the present invention,individual fuel rods have applied thereto a bar code label foridentifying the enrichment of the fuel rod. An optical reader isemployed by an operator for reading the identifying data on the fuel rodlabel. The optical reader inputs the data to a computer which comparesthe data with stored data for the particular fuel rod pattern of thefuel assembly to be loaded to match the fuel rod with the correctlocation.

Thus, to load fuel rods in the desired pattern for a BWR fuel assembly,an operator takes an individual fuel rod from a supply thereof andmanually deploys the optical scanner to read and input the identifyingdata. The computer then displays on its screen the proper location forthe fuel rod in the BWR fuel assembly. The operator then inserts thefuel rod into the location in a loading magazine which corresponds tothe proper BWR fuel assembly location. The steps are repeated tocomplete the BWR pattern of loaded fuel rods.

The above-summarized loading system of the Ahmed et al patent is a stepin the right direction toward automating the loading of fuel rods.However, the procedures required to be performed by the operator aretedious and susceptible to operator error. Consequently, a need stillexists for steps toward further automation of the loading system thatwill reduce or eliminate entirely the opportunity for operator error.

SUMMARY OF THE INVENTION

The present invention provides an automated fuel rod pattern loadingsystem designed to satisfy the aforementioned needs. The automatedloading system of the present invention employs method and apparatus forloading fuel rods into a fuel rod magazine in a particular pattern withminimum of operator assistance. No operator judgment is required toassure a correct loading pattern. Although the automated loading systemis particularly suited for loading BWR fuel rods which may differ inenrichment, it could be used for other types of fuel rods as well.

Accordingly, the present invention is directed to an apparatus forloading fuel rods in a desired pattern which comprises: (a) means in theform of a carrousel having a plurality of movable gondolas for stockingthereon fuel rods of known enrichments; (b) an elongated magazinedefining a matrix of elongated slots open at their forward ends forreceiving fuel rods; (c) a workstation defining a fuel rod feed path andincluding means for receiving successively one at a time along feed pathfuel rods from selected ones of the carrousel gondolas and verifying theidentity of the fuel rods and means for feeding successively one at atime along the feed path the verified fuel rods into selected ones ofthe slots in the magazine; and (d) an holder and indexing mechanism formovably supporting the magazine and being actuatable for moving themagazine along X-Y axes to successively align one at a time selectedones of its slots with the feed path for loading in the magazine thesuccessive fuel rods in a desired enrichment pattern.

Also, the present invention is directed to a method for loading fuelrods in a desired pattern, comprising the steps of: (a) stocking acarrousel with a supply of fuel rods of known enrichments; (b) providinga magazine defining a matrix of elongated slots open at their forwardends for receiving fuel rods; (c) defining a fuel rod feed path; (d)receiving successively one at a time along the feed path fuel rodsselected from the supply thereof; (e) verifying successively one at atime along the feed path the identity of the selected fuel rods; (f)feeding to the magazine successively one at a time along the feed paththe selected and verified fuel rods; and (g) supporting and moving themagazine along X-Y axes to successively align one at a time selectedones of said slots with the feed path for loading in the magazine thesuccessive fuel rods in a desired enrichment pattern.

These and other features and advantages of the present invention willbecome apparent to those skilled in the art upon a reading of thefollowing detailed description when taken in conjunction with thedrawings wherein there is shown and described an illustrative embodimentof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the course of the following detailed description, reference will bemade to the attached drawings in which:

FIG. 1 is a fragmentary perspective schematic view of a carrouselemployed in the fuel rod loading apparatus of the present invention.

FIG. 2 is a schematic view of components of the fuel rod loadingapparatus associated with the carrousel.

FIG. 3 is a flow chart depicting the overall sequence of operationsperformed in the fuel rod pattern loading system.

FIG. 4 is a side elevational view of a fuel rod verify and transferworkstation of the fuel rod loading apparatus of the present invention.

FIG. 5 is an end elevational view of the workstation as seen along line5--5 of FIG. 4.

FIG. 6 is a top plan view of the workstation as seen along line 6--6 ofFIG. 4.

FIG. 7 is an enlarged end elevational view of a stop gate mechanism ofthe workstation as seen along line 7--7 of FIG. 6.

FIG. 8 is an enlarged vertical sectional view of a fuel rod feedmechanism of the workstation taken along line 8--8 of FIG. 4.

FIG. 9 is a top plan view of the horizontal direction indexingcomponents of a magazine holder and indexing mechanism of theworkstation as seen along line 9--9 of FIG. 4.

FIG. 10 is a top plan view of the vertical direction indexing componentsof the magazine holder and indexing mechanism of the workstation as seenalong line 10--10 of FIG. 4.

FIG. 11 is an enlarged end elevational view of the magazine holder ofthe workstation as seen along line 11--11 of FIG. 4.

FIG. 12 is an enlarged foreshortened axial sectional view of a fuel rodpattern storage magazine employed in the fuel rod loading apparatus ofthe present invention.

FIG. 13 is a front end elevational view of the magazine as seen alongline 13--13 of FIG. 12.

FIG. 14 is a is a rear end elevational view of the magazine as seenalong line 14--14 of FIG. 12.

FIG. 15 is an enlarged cross-sectional view of the magazine taken alongline 15--15 of FIG. 12.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, like references characters designate likeor corresponding parts throughout the several views. Also in thefollowing description, it is to be understood that such terms as"forward", "rearward", "left", "right", "upwardly", "downwardly", andthe like, are words of convenience and are not to be construed aslimiting terms.

Referring now to the drawings, and particularly to FIGS. 1 and 2, thereis shown schematically the components of a fuel rod loading apparatus,generally designated 10, of the present invention employed by the fuelrod pattern loading system for carrying out the operations thereofdepicted in flow chart form in FIG. 3. In its basic components, the fuelrod loading apparatus 10 includes a fuel rod supply carrousel 12, a fuelrod verify and transfer workstation 14, a fuel rod pattern storagemagazine 16, and a magazine holder and indexing mechanism 18. The fuelrod pattern loading system employs a stand alone computer 20 whichintegrates, coordinates and controls the various operations performed bythese components of the apparatus 10.

Overall Fuel Rod Pattern Loadinq System

As depicted in the flow diagram of FIG. 3, block A denotes the initialoperation in the fuel rod pattern loading system of stocking the storageor supply carrousel 12 with fuel rods R (FIGS. 1 and 2). The carrousel12 is composed of a plurality of gondolas 22 which receive and supportstorage channels or trays 24 containing multiplicities of fuel rods Rsome of which with identical enrichments and others with differentenrichments. Preferably, any given tray 24 contains fuel rods R havingthe same enrichment so that fuel rod selection will only need to be madebetween fuel rods of different trays and not between fuel rods within asingle tray itself. The carrousel 12 also has a framework 26 movablysupporting at its opposite ends a pair of endless chains 28 (only onebeing shown) between which the gondolas 22 extend and to which theopposite ends of the gondolas 22 are attached.

The operator at the system computer 20 selects and initiates a menuoption of the software to load or stock the carrousel 12 and is promptedon the computer screen 20A to scan the fuel rod trays 24 with a bar codereader 30 to identify its contents. When this is done, the dataidentifying the tray 24 is transmitted to the database in the memory ofthe system computer 20. The operator is then prompted on the screen 20Ato place the identified tray 24 onto one gondola 22 of the carrousel 12and to scan the gondola bar code to identify on which one of thegondolas 22 the tray 24 is being placed. This sequence is repeated untilthe carrousel 12 is completely stocked. Thus, the system computer 20 isnow provided with a database of the type of fuel rods R located in eachtray 24 and where on the gondolas 22 of the carrousel 12 each particulartray is located.

Block B in FIG. 3 denotes the next operation of the fuel rod patternloading system of selecting the mini-bundle pattern which begins actualloading of a particular mini-bundle pattern of fuel rods R into thestorage magazine 16. Once the pattern has been selected, the computer 20will prompt the operator on the screen 20A to take certain actions andwill control the operations of the verify and transfer workstation 14and of the indexing mechanism 18 in a sequence or cycle which will berepeated a number of times, for instance sixteen times for loading a 4×4BWR mini-bundle, to accomplish substantially automatic loading of fuelrods in the storage magazine 16 based on a design matrix already enteredin the database of the system computer 20.

Again, the operator at the system computer 20 selects and initiates amenu option of the software to initiate loading of the magazine byselecting the mini-bundle pattern. The computer screen 20A prompts theoperator to move a mini-bundle storage magazine 16 into place. Next, theoperator reads and keys in the pattern identification number engraved ona BWR fuel assembly top tie plate and then attaches this plate to themagazine holder 32. This keyed-in number identifies to the computer whattype of mini-bundle pattern is to be loaded into the magazine 16. Thecomputer 20 in its database then runs a check of the carrousel inventoryto verify that the correct quantity and mix of fuel rods R exist on thecarrousel 12 for that type of mini-bundle pattern.

Blocks C and D in FIG. 3 denote the first two operations in a sequenceof the fuel rod pattern loading system which is repeated until loadingof the selected mini-bundle pattern is completed. These first twooperations involve, first, the computer 20 selecting the firstappropriate gondola 22 of the carrousel 12 having the desired initialtype of fuel rod R to be loaded in the selected mini-bundle pattern and,second, the operator actually manually taking a fuel rod by its leadingend from the tray 24 on the selected gondola 22 and placing the rod endinto the verify and transfer workstation 14. The system computer 20 isinterfaced with the carrousel 12 so as to operate the same to causemovement of the gondolas 22 so as to bring the first appropriate one ofthe gondolas into general alignment with the workstation 14 as seen inFIG. 2. The screen 20A of the system computer 20 then prompts theoperator to place one of the fuel rods from the selected gondola intothe workstation 14.

Block E in FIG. 3 denotes the next operation of the repeated loadingsequence of the fuel rod pattern loading system. The operation involvesverifying that the correct fuel rod has been placed in the workstation14 by the operator. Basically, the workstation 14 includes a stop gatemechanism 32 near its upstream end and a fuel rod feed mechanism 34 nearits downstream end. The stop gate mechanism 32 is initially positionedto block and prevent movement of the fuel rod R downstream by theoperator to the feed mechanism 34 until it is verified by the computer20 as being of the correct type of enrichment.

To verify the fuel rod R, the operator manually uses the bar code reader30 to read and input the rod bar code label. The computer 20 thenverifies a correct rod identification number and associates the numberto the enrichment of the rod. From this data and that of the selectedmini-bundle pattern, the computer 20 will control the indexing mechanism18 to move the magazine 16 to the correct position for insertion of therod into the proper slot in the magazine 16.

Block F in FIG. 3 denotes the another operation of the repeated loadingsequence of the fuel rod pattern loading system wherein the magazine 16is properly positioned so that the correct magazine slot in which toinsert the fuel rod is aligned with the feed mechanism 34 on theworkstation 14. The computer 20 controls operation of the magazineholder and indexing mechanism 18 to move the magazine with respect toX-Y axes until the appropriate slot in the magazine is aligned with therod. After the fuel rod's bar code has been read and verified and afterthe magazine has been indexed into the correct position, the mechanicalstop gate mechanism 32 is activated to move and unblock the path P ofthe fuel rod R through the workstation 14 so that the rod can then bemanually move into engagement with the fuel rod feed mechanism 34.

Block G in FIG. 3 denotes the final operation of the fuel rod patternloading system in its repeated loading sequence. In this operation, theverified fuel rod is driven or loaded into the proper magazine slot byoperation of the feed mechanism 34. Block H in FIG. 3 denotes that theoperations of blocks C to G are repeated until loading in the magazine16 of the selected minibundle pattern of fuel rods is completed. In therepetition of the sequence, the positioning of the magazine 16 can takeplace concurrently as the appropriate gondola 22 is being located andmoved into alignment with the workstation 14.

Upon completion, the system computer 20 creates a mini-bundleidentification number by combining the tie plate engraved number withthe identification numbers of the sixteen fuel rods. A workstationprinter (not shown) then prints a color coded routing card for themagazine which includes the fuel rod identification numbers,enrichments, and actual magazine loading pattern.

Fuel Rod Loading Apparatus

In addition to the fuel rod supply carrousel 12 which was described indetail above, as schematically depicted in FIG. 2 the fuel rod loadingapparatus 10 also includes the above- mentioned fuel rod verify andtransfer workstation 14, the fuel rod pattern storage magazine 16, andthe magazine holder and indexing mechanism 18. The gondolas 22 of thecarrousel 12 stock fuel rods R of known enrichments in trays 24 and aremovably mounted to bring a selected tray 24 of rods into generalalignment with the workstation 14. The magazine 16 defines a matrix ofelongated slots 16A open at their forward ends for receiving fuel rodsR. The workstation 14 defines the fuel rod feed path P extending betweenthe carrousel 12 and the magazine 16 and is adapted to receivesuccessively one at a time along the feed path P, at its upstream end,fuel rods R from selected ones of the carrousel gondolas 22. Theworkstation 14 includes an optical scanning and reading unit 35 locatedalong the feed path P for verifying the identity of the fuel rods Rsuccessively one at a time. The workstation 14 also includes the fuelrod feed mechanism 34 for successively feeding one at a time along thefeed path P the verified fuel rods into selected ones of the slots 16Ain the magazine 16. The magazine holder and indexing mechanism 18movably supports the magazine 16 and is actuatable for moving themagazine 16 in a generally vertical plane along X-Y axes to successivelyalign one at a time selected ones of its slots 16A with the feed path Pfor loading in the magazine 16 the successive fuel rods R in a desiredenrichment pattern.

Referring now to FIGS. 4-8, the fuel rod verify and transfer workstation14 of the loading apparatus 10 is illustrated in greater detail. Theworkstation 14 includes a frame 36 constructed of a plurality ofvertical legs 38 supporting a top horizontal platform 40 and reinforcedby a plurality of cross members 42 which extend between and interconnectthe legs 38. Mounted to the frame platform 40 in alignment along thefuel rod path P and arranged from the upstream to downstream ends of theplatform 40 are an optical scanner 44 of the unit 35 with which the barcode reader 30 of the unit 35 is used, a pair of guide idler rollers46,48 rotatably mounted on by respective supports 46A,48A at upstreamand downstream sides of the scanner 44, the stop gate mechanism 32disposed between the scanner 44 and the downstream guide roller 48, therod feed mechanism 34, and a stationary rod guide 50 and rod sensor 52disposed between the guide roller 48 and the upstream entry end of thefeed mechanism 34 for turning "on" the feed mechanism 34 in response tosensing the presence of a fuel rod.

In FIGS. 6 and 7, the arrangement and construction of the stop gatemechanism 32 of the workstation 14 is illustrated in detail. The stopgate mechanism 32 is disposed along the feed path P between the scanningand reading unit 35 (which includes the bar code reader 30 and theoptical scanner 44) used to verify the identity of the fuel rods R andthe fuel rod feed mechanism 34 of the workstation 14. In particular, thestop gate mechanism 32 is located immediately upstream of the downstreamguide idler roller 48 and is operable relative to the feed path Pbetween a blocking position shown in solid line in FIG. 6 and anunblocking position shown in dashed line in FIG. 6 for respectivelypreventing and allowing passage of a fuel rod R.

The stop gate mechanism 32 includes a bracket 54 attached on theplatform 40 of the frame 36 and mounting an arm 56 for reciprocatorysliding movement toward and away from the feed path P, an actuator 58 inthe form of an air cylinder mounted to the bracket 54 and connected toone end of the slide arm 56. The actuator 58 is operable for moving theslide arm 56 between extended and retracted positions shown respectivelyin solid and dashed line forms in FIG. 6. A gate 60 in the form of aflat plate mounted to an opposite end of the slide arm 56 is disposedacross the feed path P when the arm 56 is at its extended position andis withdrawn away from the feed path P when the arm 56 is at itsretracted position. Operation of the actuator 58 is controlled by thesystem computer 20. The actuator 58 is actuated to retract the arm 56and gate 60 upon verification of the identity of the fuel rod whoseleading end is currently placed across the scanning and reading unit 35.

In FIGS. 4-6 and 8, the arrangement and construction of the fuel rodfeed mechanism 34 of the workstation 14 is illustrated in detail. Thefeed mechanism 34 is located downstream of the stationary rod guide 50and rod sensor 52 which, in turn, are disposed downstream of the oneguide roller 48. When the feed path P is unblocked by the stop gatemechanism 32, the leading end of the fuel rod R is manually slid ormoved by the operator onto the guide roller 48, then through the taperedhole 62 in the rod guide 50 and past the rod sensor 52 into the entryend of the feed mechanism 34. The computer 20 receives a signal from therod sensor 52 and activates operation of the feed mechanism 34 inresponse to sensing the arrival of the fuel rod.

The feed mechanism 34 includes a pair of housings 64 mounted to theframe platform 40 in spaced apart relation and having respective shafts66 rotatably journaled within and extending horizontally through thehousings 64. Along one side of the housings 64, respective drive rollers68 are attached to the protruding ends of the shafts so as to be spacedapart along the feed path P. Along the other side of the housings 64,respective driven pulleys 70 are attached to the opposite protrudingends of the shafts 66. The mechanism 34 also includes a motor 72attached to the underside of the platform 40 between and below thehousings 64. The motor 72 has a rotary output drive shaft 74 with adrive pulley 76 fixed thereon. A drive belt 78 is entrained about thedrive pulley 76 and driven pulleys 70. An idler pulley 80 for adjustingtension in the belt 78 is rotatably mounted by a bracket 82 mounted tothe platform 40 between the driven pulleys 70. Thus, it will beunderstood that the drive rollers 68 are rotated by operation of themotor 72 via their mounting on the same rotatable shafts as the drivenpulleys 70.

The feed mechanism 34 also includes a superstructure 84 mounted aboveand bridging between the housings 64 and respective actuators 86 in theform of air cylinders supported on the superstructure 84. The piston rodends 86A of the actuators 86 support guide rods 88 and rotatably mountpressure rollers 90 such that the pressure rollers 90 are locateddirectly above and aligned with the respective drive rollers 68. Uponoperation of the feed mechanism 34, the actuators 86 extend from theirretracted conditions seen in FIGS. 4, 5 and 8, and move the pressurerollers 90 toward the lower drive rollers 68 for engaging and pinching afuel rod R therebetween and cause feeding of the rod along the feed pathP toward the magazine 16. The sensor 52 causes operation of theactuators 86 upon sensing the arrival of the fuel rod at the entry endof the feed mechanism 34.

In FIGS. 4, 5 and 8, the arrangement and construction of a fuel rod feedassist mechanism 92 of the workstation 14 is also illustrated. The feedassist mechanism 92 is used in conjunction with the fuel rod feedmechanism 34 to ensure that the individual fuel rods R are insertedcompletely in the magazine 16. The feed assist mechanism 92 includes anactuator 94 in the form of an air cylinder mounted horizontally to thesuperstructure 84 between the pressure rollers 90 and above and offsetfrom the feed path P. Also, the feed assist mechanism 92 includes aguide structure 96 mounted to the superstructure 84 parallel to andbelow the actuator 94, a cam member 98 mounted to the guide structure 96adjacent its downstream end, and a device composed of a connector 100and a finger 102 pivotally mounted to one side of the connector 100. Theconnector 100 is attached at its upper end to the piston rod end 94A ofthe actuator 94 and at its middle and lower end to a pair ofhorizontally movable telescopible members 104 of the guide structure 96.

Once the drive rollers 68 and pressure rollers 90 of the feed mechanism34 have driven a fuel rod most of the way into the magazine 16 and asfar downstream as they can, the feed assist mechanism 92 takes over andis operated to continue driving of the fuel rod completely into themagazine. Specifically, its actuator 94 is extended from the retractedposition shown in FIG. 4 and toward a hoop-shaped bracket 106 of themagazine holder and indexing mechanism 18. As the actuator piston rodend 94A extends, it carries the connector 100 with it which moves thepivotal finger 102 off the cam element 98 allowing the finger to pivotby gravity clockwise and downwardly into the feed path P upstream of thetrailing end of a fuel rod. Continued extension of the actuator 94brings an end 102A of the finger into contact with the trailing end ofthe fuel rod to impart sufficient driving motion thereto to fully insertthe fuel rod in the magazine 16. Retraction of the actuator 94 willreturn the finger 102 to its position seen in FIG. 4 in which it ispivoted counterclockwise out of the feed path P.

Turning now to FIGS. 4, 5, and 9-11, there is illustrated in detail thearrangement and construction of the magazine holder and indexingmechanism 18 of the fuel rod loading apparatus 10. The indexingmechanism 18 is located downstream of and adjacent to the exit end ofthe feed mechanism 34 and at the front end of the magazine 16. Theindexing mechanism 18 basically includes the above-mentioned hoop-shapedbracket 106, upper indexing means 108 for moving the bracket 106 andmagazine 16 in the horizontal X direction, and lower indexing means 110for moving the upper indexing means 108, bracket 106 and magazine 16 inthe vertical Y direction.

As best seen in FIG. 11, the bracket 106 of the indexing mechanism 18includes a generally U-shaped portion 106A rotatably mounted about avertical axis to an upper horizontal plate 112 and a circular portion106B pivotally mounted about a horizontal axis to the U-shaped portion106. The circular bracket portion 106B receives and attaches to thefront end portion of the magazine 16 for supporting the same. Movementof the brackets portions 106A,106B about the respective orthogonalhorizontal X and vertical Y axes results when the upper plate 112mounting the bracket 106 is correspondingly moved vertically andhorizontally.

As best seen in FIGS. 4 and 9, the upper indexing means 108 of theindexing mechanism 18 includes the upper plate 112 which mounts thehoop-shaped bracket 106, a lower horizontal plate 114 which underliesand is spaced below the upper plate 112, a pair of spaced aparthorizontal guide members 116 and a first actuator 118. The guide members116 are mounted upon the lower plate 114 along opposite sides of thefirst actuator 118. The guide members 116, in turn, support and guidemovement of upper plate 112 along the horizontal X axis relative to thelower plate 114. The first actuator 118 includes a motor 120 mounted onan extension 114A of the lower plate 114 and an elongated externallythreaded screw shaft 122 attached to and rotatably driven by the motor120. The screw shaft 122, in turn, is coupled to an internally threadedhousing 124 fixed to the underside of the upper plate 112. In suchmanner, the first actuator 118 is mounted to the lower plate 114 anddriving coupled to the upper plate 112 and operable to cause movement ofthe upper plate 112 along the path of the horizontal guide members 116relative to lower plate 114 and along the horizontal X axis. A motiontransducer device 126 is provided adjacent at end of the screw shaft 122opposite the motor 120 for providing feedback of the position of theshaft to the computer 20 for control purposes.

As best seen in FIGS. 4 and 10, the lower indexing means 110 of theindexing mechanism 18 includes a horizontal platform 128 which underliesand is spaced below the lower plate 114 of the upper indexing means 110,a pair of spaced apart vertical guide members 130 and a second actuator132. The guide members 130 are mounted upon the horizontal platform 128along opposite sides of the second actuator 132. The guide members 130,in turn, support and guide movement of the lower plate 114 of the upperindexing means 108 (and therewith all of the rest of the componentsthereof) along the vertical Y axis relative to the platform 128. Thesecond actuator 132 includes a motor 134 mounted on one of the framecross members 42 adjacent the platform 128 and a pair of intermeshingexternally-threaded horizontal and vertical screw shafts 136,138, withthe horizontal screw shaft 136 being attached to and rotatably driven bythe motor 134 and the vertical screw shaft 138, in turn, being coupledto an internally threaded housing 140 fixed to the underside of thelower plate 114. In such manner, the second actuator 132 is mounted tothe horizontal platform 128 and driving coupled to the lower plate 114and operable to cause movement of the lower plate 114 along the path ofthe vertical guide members 130 relative to platform 128 and along thevertical Y axis. Another motion transducer device 142 is providedadjacent at end of the horizontal screw shaft 136 opposite the motor 134for providing feedback of the position of the shaft to the computer 20for control purposes.

In FIGS. 12-15, the construction of the fuel rod pattern storagemagazine 16 is illustrated in detail. The magazine 16 includes agenerally cylindrical shell 144 with circular opposite end plates146A,146B and spaced intermediate plates 146C being interconnected bylongitudinally extending tie rods 148. The end and intermediate plates146A-146C having a matrix of openings 150 therein which define themini-bundle fuel rod pattern. Elongated hollow tubes 152 (only one beingfragmentarily shown in FIG. 12) are mounted through the openings 150 andextend through the shell 144 for defining the slots 16A of the magazine16 for receiving and holding the fuel rods R in the desired enrichmentpattern as determined by the computer-controlled operation of theindexing mechanism 18.

It is thought that the present invention and many of its attendantadvantages will be understood from the foregoing description and it willbe apparent that various changes may be made in the form, constructionand arrangement thereof without departing from the spirit and scope ofthe invention or sacrificing all of its material advantages, the formhereinbefore described being merely a preferred or exemplary embodimentthereof.

We claim:
 1. Apparatus for loading fuel rods in a desired pattern,comprising:(a) a supply of fuel rods of known enrichments; (b) anelongated magazine defining a matrix of positions for receiving fuelrods; (c) a workstation defining a fuel rod feed path and including(i)means for receiving successively one at a time along said feed path fuelrods from said supply thereof and verifying the identity of the fuelrods, (ii) means for feeding successively one at a time along said feedpath the verified fuel rods into selected ones of the positions in saidmagazine, and (iii) means disposed along the feed path between said fuelrod identity verifying means and said fuel rod feeding means formovement between blocking and unblocking positions relative to the feedpath to respectively prevent passage of a fuel rod to said feeding meansuntil the identify of the fuel rod is verified as correct and to allowsuch passage of the fuel rod after such verification is made; and (d) anholder and indexing mechanism for movably supporting said magazine andbeing actuatable for moving the magazine along X-Y axes to successivelyalign one at a time selected ones of said positions with said feed pathfor loading in said magazine the successive fuel rods in a desiredenrichment pattern.
 2. The apparatus as recited in claim 1, wherein saidsupply is a carrousel having a plurality of movable gondolas forstocking thereon the fuel rods of known enrichments.
 3. The apparatus asrecited in claim 1, wherein said positions are defined by a plurality ofelongated slots in said magazine being open at their forward ends forreceiving fuel rods.
 4. The apparatus as recited in claim 1, whereinsaid means disposed for movement between blocking and unblockingpositions is a stop gate mechanism.
 5. The apparatus as recited in claim4, wherein said stop gate mechanism includes:an arm mounted for slidingreciprocatory movement; an actuator connected to said arm and beingoperable for moving said arm between extended and retracted positions;and a gate mounted to said arm and being disposed in said blockingposition across the feed path when said arm is at its extended positionand being withdrawn away from the feed path to said unblocking positionwhen said arm is at its retracted position.
 6. The apparatus as recitedin claim 1, wherein said feeding means includes:a lower pair ofrotatably-mounted drive rollers spaced apart along the feed path; andmeans coupled to said rollers for driving the same.
 7. The apparatus asrecited in claim 6, wherein said feeding means includes:an upper pair ofrotatably-mounted pressure rollers spaced along the feed path and eachaligned above one of said lower drive rollers; and means for rotatablymounting said pressure rollers and being actuatable for moving saidpressure rollers toward said lower drive rollers for engaging andpinching a fuel rod therebetween to cause feeding of the rod along thefeed path toward said magazine.
 8. The apparatus as recited in claim 7,wherein said workstation includes a sensor disposed along the feed pathupstream of said feeding means for sensing the arrival of a fuel rod andin response thereto being operable for actuating said pressure rollermounting means.
 9. The apparatus as recited in claim 1, wherein saidworkstation further includes a feeding assist mechanism disposed alongthe feed path adjacent a downstream end of said fuel rod feeding meansand being operable for contacting a trailing end of a fuel rod to impartsufficient driving motion thereto to fully insert the fuel rod in saidmagazine.
 10. The apparatus as recited in claim 9, wherein said feedingassist mechanism includes:a stationary cam member; a pivotally-mountedfinger; and means for moving said finger relative to and in contact withsaid cam member for causing pivoting of said finger along a drive pathfor contacting the trailing end of the fuel rod to impart the drivingmotion thereto.
 11. The apparatus as recited in claim 1, wherein saidmagazine holder and indexing mechanism includes:a bracket mounting saidmagazine; first means for supporting said bracket and being actuatablefor causing movement of said bracket along one of the X-Y axes; andsecond means for supporting said first means and being actuatable forcausing movement of said first means and said bracket therewith alongthe other of said X-Y axes.
 12. The apparatus as recited in claim 11,wherein said first means includes:an upper plate mounting said bracket;a lower plate underlying and spaced from said upper plate; a pair ofspaced apart first guide members coupled between said lower and upperplates for sliding movement along said one of said axes relative to saidlower plate; and a first actuator mounted to one of said plates anddriving coupled to the other of said plates and being operable to causemovement of said one plate relative to said other plate along said oneof said axes.
 13. The apparatus as recited in claim 12, wherein saidfirst guide members are mounted on said lower plate and support andguide said upper plate for movement along said X axis relative to saidlower plate.
 14. The apparatus as recited in claim 12, wherein saidsecond means includes:a platform underlying and spaced from said lowerplate of said first means; a pair of second spaced apart guide memberscoupled between said lower plate and said platform for guiding saidlower plate for sliding movement along said other of said X-Y axesrelative to said platform; and a second actuator mounted to one of saidlower plate and said platform and driving coupled to the other thereofand being operable to cause movement of one relative to the other alongsaid other of said X-Y axes.
 15. The apparatus as recited in claim 14,wherein said second guide members are mounted to and below said lowerplate and guide said lower plate for movement along said Y axis towardand away from said platform.
 16. The apparatus as recited in claim 1,wherein said magazine holder and indexing mechanism includes:a bracketpivotally mounting said magazine at a forward portion thereof aboutorthogonal horizontal X and vertical Y axes; first means for supportingsaid bracket and being actuatable for causing movement of said bracketalong one of said axes resulting in movement of said magazine along saidone of said axes; and second means for supporting said first means andbeing actuatable for causing movement of said first means and saidbracket therewith along the other of said axes resulting in movement ofsaid magazine along said other of said axes.
 17. Apparatus for loadingfuel rods in a desired pattern, comprising:(a) a carrousel having aplurality of movable gondolas for stocking thereon fuel rods of knownenrichments; (b) an elongated magazine defining a matrix of elongatedslots being open at their forward ends for receiving fuel rods; (c) aworkstation defining a fuel rod feed path and including(i) means forreceiving successively one at a time along said feed path fuel rods fromselected ones of said gondolas of said carrousel and verifying theidentity of the fuel rods, (ii) means for feeding successively one at atime along said feed path the verified fuel rods into selected ones ofthe slots in said magazine, and (iii) means disposed along the feed pathbetween said fuel rod identity verifying means and said fuel rod feedingmeans for movement between blocking and unblocking positions relative tothe feed path to respectively prevent passage of a fuel rod to saidfeeding means until the identify of the fuel rod is verified as correctand to allow such passage of the fuel rod after such verification ismade; and (d) an holder and indexing mechanism for movably supportingsaid magazine and being actuatable for moving the magazine along X-Yaxes to successively align one at a time selected ones of said slotswith said feed path for loading in said magazine the successive fuelrods in a desired enrichment pattern.
 18. The apparatus as recited inclaim 17, wherein said means disposed for movement between blocking andunblocking positions is a stop gate mechanism.
 19. The apparatus asrecited in claim 17 wherein said feeding means includes:a lower pair ofrotatably-mounted drive rollers spaced apart along the feed path; meanscoupled to said rollers for driving the same; an upper pair ofrotatably-mounted pressure rollers spaced along the feed path and eachaligned above one of said lower drive rollers; and means for movablemounting said pressure rollers and being actuatable for moving saidpressure rollers toward said lower drive rollers for engaging andpinching a fuel rod therebetween to cause feeding of the rod along thefeed path toward said magazine.
 20. The apparatus as recited in claim19, wherein said workstation includes a sensor disposed along the feedpath upstream of said feeding means for sensing the arrival of a fuelrod and in response thereto being operable for actuating said pressureroller mounting means.
 21. The apparatus as recited in claim 17, whereinsaid workstation further includes a feeding assist mechanism disposedalong the feed path adjacent a downstream end of said fuel rod feedingmeans and being operable for contacting a trailing end of a fuel rod toimpart sufficient driving motion thereto to fully insert the fuel rod insaid magazine.
 22. The apparatus as recited in claim 17, wherein saidmagazine holder and indexing mechanism includes:a bracket pivotallymounting said magazine at a forward portion thereof about orthogonalhorizontal X and vertical Y axes; first means for supporting saidbracket and being actuatable for causing movement of said bracket alongsaid horizontal X axis resulting in movement of said magazine along saidhorizontal X axis; and second means for supporting said first means andbeing actuatable for causing movement of said first means and saidbracket therewith along said vertical Y axis resulting in movement ofsaid magazine along said vertical Y axis.